István Antal

Quantitative determination of crystallinity of alpha-lactose monohydrate by Near Infrared Spectroscopy (NIRS)

The purpose of this study was to determine quantitatively the crystallinity in crystalline/amorphous powder mixtures of lactose, to asses the capability of Near Infrared Spectroscopy (NIRS) for quantitative determination of crystallinity and to compare the accuracy of the NIRS method with that of conventional X-ray powder diffraction (XRPD). Amorphous lactose was prepared by spray drying. Samples with different crystallinity were prepared by physical mixing of 100% amorphous and 100% crystalline materials. The samples were characterized by XRPD and NIRS. Analysis was performed on the data sets by multiple linear regression (MLR). There is a close correlation between the predicted and the actual crystallinity of physical mixtures of crystalline and amorphous lactose, determined by NIRS (R(2)=0.9994). NIRS results were compared to the XRPD using the same sample sets. The correlation coefficients was 0.9981. The results showed that NIRS is an useful method for accurately determining low quantities of the crystalline lactose in a physical mixture. Therefore, NIRS can be used for the quantitative determination of crystallinity of materials during pharmaceutical procedures.

Evaluation of mathematical models describing drug release from lipophilic matrices

Potassium chloride, as a highly watersoluble model drug was embedded into wax to produce sustained release dosage form. Samples were coated with different core:wall ratios to control the dissolution profile. The drug release from coated samples was tested by the rotating paddle method of USP and the dissolution data were analyzed assuming different kinetic models. Increasing the quantity of coating material may modify the drug liberation which was demonstrated by the correlation between proportion of the embedding material and mean dissolution time. It can be concluded that changing the quantity of embedding material both the dissolution rate and kinetic profile can be controlled.

Evaluation of Drug Release From Coated Pellets Based on Isomalt, Sugar, and Microcrystalline Cellulose Inert Cores

The objective of the present study was to investigate the effect of the pellet core materials isomalt, sugar, and microcrystalline cellulose on the in vitro drug release kinetics of coated sustained-release pellets as well as to evaluate the influence of different ratios of polymethacrylate copolymers exhibiting different permeability characteristics on the drug release rate. For characterization of the drug release process of pellets, the effect of osmolality was studied using glucose as an osmotically active agent in the dissolution medium. The pellet cores were layered with diclofenac sodium as model drug and coated with different ratios of Eudragit® RS30D and Eudragit® RL30D (ERS and ERL; 0:1 and 0.5:0.5 and 1:0 ratio) in a fluid bed apparatus. Physical characteristics such as mechanical strength, shape, and size proved that the inert cores were adequate for further processing. The in vitro dissolution tests were performed using a USP Apparatus I (basket method). The results demonstrated that, besides the ratio of the coating polymers (ERS/ERL), the release mechanism was also influenced by the type of starter core used. Sugar- and isomalt-type pellet cores demonstrated similar drug release profiles.

Dissolution and diffuse reflectance characteristics of coated theophylline particles

The aim of the present study was to investigate how the dissolution and diffuse reflectance characteristics of theophylline microcapsules were influenced by the changes in the thickness and by the plasticizer content of coating. Microencapsulation was carried out in laboratory fluidized-bed system using water dispersable Eudragit-type film coating polymer. United States Pharmacopeia rotating paddle method was applied for the in vitro dissolution study. The dissolution profile of the produced microcapsules was evaluated by Weibull distribution. The effect of the thickness of coating and that of the plasticizer content on the dissolution kinetics was modelled by a second-order polynomial equation fitted to the data gathered by a face-centered central composite statistical design. It was found that both of the examined coating parameters influenced the drug release kinetics. The diffuse reflectance spectra of the coated particles indicated the changes in coating parameters without destructive analysis of samples.

Spontaneous and visible light-induced ultraweak photon emission from rat eyes

Here, we present the first experimental in vitro evidence of the existence of spontaneous and visible light-induced ultraweak photon emission from freshly isolated whole eye, lens, vitreous humor, and retina samples from rats. These results suggest that the photochemical source of retinal discrete noise, as well as retinal phosphenes, may originate from natural bioluminescent photons within the eyes. During normal vision, the eyes are continuously exposed to ambient powerful photons that pass through various parts of the eyes, which can produce ultraweak delayed bioluminescent photons that arise from diverse parts of the eyes. Although the importance and possible role of ambient light-induced permanent delayed photons (within different parts of the eyes) during vision requires further investigation, our study may provide evidence of an origin of discrete dark noise and retinal phosphenes.

Aqueous solvent system for solubilization of azole compounds

Azoles have a wide spectrum antimycotic activity, but due to some derivatives exhibiting poor water solubility their parenteral administration is limited. The influence of solubilizers on the aqueous solubility of the itraconazole, ketoconazole and miconazole was investigated in order to enhance their solubility for a possible parenteral dosage form. The solubilizer effect of acetate, phosphate and gluconate solutions were studied, along with ethanol, glycerol, macrogol 400, propylene glycol and surfactants, such as polysorbate 20, 60, 80 and sodium taurocholeate. The solubilizing effect of these excipients in binary or ternary combinations was also studied. An HPLC method was used for the solubility assay of the azoles. All of the assessed excipients showed considerable solubility enhancement characteristics, moreover the binary and ternary combinations showed synergistic effects solubilizing more miconazole than what they solubilized separately. Ternary combinations were capable of solubilizing more than 30 mg/ml miconazole, and more than 135 mg/ml of ketoconazole, which in both cases is a very substantial increase in solubility compared to their water solubility. The amount of solubilized drugs may well be used therapeutically, and the formulated solvent system can serve as a base for parenteral solutions.

Multiple ABC Transporters Efflux Baicalin

Baicalein, the aglycone formed by hydrolysis of baicalin in the intestine, is well absorbed by passive diffusion but subjected to extensive intestinal glucuronidation. Efflux of baicalin, the low passive permeability glucuronide of baicalein from enterocytes, likely depends on a carrier‐mediated transport. The present study was designed to explore potential drug–herb interaction by investigating the inhibitory effect of baicalin on the transport of reporter substrates by transporters and to identify the transporters responsible for the efflux of baicalin from enterocytes and hepatocytes. The interaction of baicalin with specific ABC transporters was studied using membranes from cells overexpressing human BCRP, MDR1, MRP2, MRP3 and MRP4. Baicalin was tested for its potential to inhibit vesicular transport by these transporters. The transport of baicalin by the selected transporters was also investigated. Transport by BCRP, MRP3 and MRP4 was inhibited by baicalin with an IC50 of 3.41 ± 1.83 μM, 14.01 ± 2.51 μM and 14.39 ± 5.69 μM respectively. Inhibition of MDR1 (IC50 = 94.84 ± 31.10 μM) and MRP2 (IC50 = 210.13 ± 110.49 μM) was less potent. MRP2 and BCRP are the apical transporters of baicalin that may mediate luminal efflux in enterocytes and biliary efflux in hepatocytes. The basolateral efflux of baicalin is likely mediated by MRP3 and MRP4 both in enterocytes and hepatocytes. Via inhibition of transport by ABC transporters, baicalin could interfere with the absorption and disposition of drugs. Copyright

In vitro simulation of food effect on dissolution of deramciclane film-coated tablets and correlation with in vivo data in healthy volunteers

The in vitro dissolution profiles of deramciclane 30 mg film-coated tablets, an acid-labile new 5-HT receptor antagonist, were studied under simulated fasting and fed conditions. Artificial gastric juice with pH adjusted to that of fasting conditions was applied either alone or after adding different dietary components. The use of the USP dissolution apparatus II (paddle method) showed that the presence of dietary components has markedly affected the amount of unchanged drug dissolved. As a similar tendency had been observed in food-effect studies in healthy volunteers, cumulative area under the curve (AUC(cum)) for both fed and fasting conditions were compared and an in vitro--in vivo correlation (IVIVC) was evaluated. A linear relationship was established between logarithmic in vivo blood sampling time and in vitro dissolution time assigned to equal AUC(cum) ratios (AUC(cum, fed)/AUC(cum, fasting)). Despite its limitations, in vitro modelling of in vivo conditions might help provide a base for predicting in vivo drug behaviour.

In vitro food-drug interaction study: Which milk component has a decreasing effect on the bioavailability of ciprofloxacin?

The purpose of the present work was developing an in vitro dissolution test to highlight the possible molecular background causing ciprofloxacin (CPFX)-milk interaction. The in vitro dissolution of CPFX from film-coated tablets (Ciprinol) 500mg) was examined at different pH values, simulating certain parts of the gastrointestinal tract, in the presence of water, low-fat milk, casein- or calcium enriched water. In order to determine the amount of dissolved CPFX, solid phase extraction sample preparation followed by high performance liquid chromatography coupled with mass spectrometry was applied. Comparing the dissolution efficiency values in various media, it can be concluded, that casein has a more pronounced effect on the absorbable amount of the antibiotic at each pH value studied, than calcium. In the case of concomitant intake of CPFX film-coated tablet and milk or other dairy products not only the complexation with calcium, but also the adsorption of CPFX on the surface of proteins decreases the absorbable amount of CPFX.

Comparative evaluation of the effect of cyclodextrins and pH on aqueous solubility of apigenin

The aqueous solubility of a flavonoid, apigenin, was studied in the presence of first generation cyclodextrins (α-CyD, β-CyD, γ-CyD), ionic and nonionic synthetic derivatives of β-CyD, namely SBE-β-CyD, HP-β-CyD and RM-β-CyD at various physiological pH. The order of solubility enhancement was as follows: RM-β-CyD>SBE-β-CyD>γ-CyD>HP-β-CyD>β-CyD>α-CyD. The phase solubility diagrams of HP-β-CyD and SBE-β-CyD indicated Higuchi AL subtype behavior, suggesting 1:1 stoichiometry of the complex. In contrast, AP subtype, so higher order complex formation can be assumed in the case of RM-β-CyD and γ-CyD. The formation of inclusion complexes has been confirmed by absorption and fluorescence spectroscopic measurements. Increased antioxidant activity was observed due to the inclusion complexes. These results prove that synthetic derivatives of β-CyD will be potentially useful excipients in the development of drug delivery systems for healthcare products containing flavonoids.